How does recording interviews and interrogations facilitate or hinder the law enforcement objective of obtaining admissions and confessions?
Recording interviews and interrogations does not typically help to get confessions and admissions. It does not make a suspect more likely to confess. What it does do is to make it much more likely that the confession will stand up in court.
Many police officers are enthusiastic about the practice of recording interviews and interrogations. They like it because it allows them to show a jury the actual video or play for them the actual audio of the interview. This means there is no chance of the defense disputing the words of the confession. It means that there is no chance that there will be conflict about what the officers did or said to elicit the confession. It also means that juries will get to see the demeanor of the suspect and draw their own conclusions.
For these reasons, recording interrogations does further police objectives. However, it does not really make it more likely that a confession will be obtained. Instead, it helps to ensure that confession that are obtained will stand up in court.